Brazing bond type diamond tool with excellent cuttability and method of manufacturing the same

ABSTRACT

The present disclosure provides a brazing bond type diamond tool having excellent cuttability and a method of manufacturing the same. The diamond tool includes a shank having a body and a tip portion formed along an edge of the body, and a brazing bond layer formed on the tip portion of the shank to secure diamond particles with a brazing bond. The tip portion is thinner than the body and is integrally formed with the body.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. §119 of KoreanPatent Application No. 10-2011-0090504 filed on Sep. 7, 2011 in theKorean Intellectual Property Office, the entirety of which disclosure isincorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a technique for manufacturing a diamondtool, and, more particularly, to a brazing bond type diamond tool whichhas improved cuttability through a unique shank structure, and a methodof manufacturing the same.

2. Description of the Related Art

A general diamond tool is manufactured by welding a metal powdersintered compact having diamond particles to a shank constituting a mainbody of the diamond tool. The metal powder sintered compact acts as abonding material for securing the diamond particles.

Such a diamond tool has a problem with low impact strength.

To solve this problem, Korean Patent Publication No. 10-2000-0053707(published on Sep. 5, 2000) discloses a technique of forming a brazingbond by depositing a slurry solution of a brazing metal bond onto asubstrate and dispersing diamond particles therein, followed by heatingto a temperature of about 1300° C. or less.

For the diamond tool manufactured by the method disclosed in thispublication, a brazing bond layer is formed on a tip portion formedalong an edge of a shank. The brazing bond layer includes a brazing bondand diamond particles. Accordingly, a cutting section of the diamondtool participating in cutting operation has a very high thickness, whichis determined by the sum of the thickness of the tip portion and thethicknesses of the brazing bond layer at both sides of the tip portion.

Thus, considering that the diamond tool has increased cuttability withdecreasing thickness of the cutting section until it reaches a certainthickness value, the brazing bond type diamond tool does not have highcuttability.

BRIEF SUMMARY

Embodiments of the present invention provide a brazing bond type diamondtool which has improved cuttability through a unique shank structure anda method of manufacturing the same.

In accordance with one aspect of the present invention, a diamond toolincludes a shank having a body and a tip portion formed along an edge ofthe body; and a brazing bond layer formed on the tip portion of theshank to secure diamond particles with a brazing bond. Here, the tipportion is thinner than the body of the shank.

The body of the shank may have a thickness ranging from 1.0 mm to 3.0mm.

The diamond particles may have an average particle diameter ranging from25 to 50 mesh in consideration of improved cuttability.

In accordance with another aspect of the present invention, a method ofmanufacturing a diamond tool includes: (a) preparing a shank including abody and a tip portion formed along an edge of the body, the tip portionbeing thinner than the body; (b) depositing a metal powder for forming abrazing bond on the tip portion of the shank; (c) setting diamondparticles on the tip portion having the metal powder deposited thereon;and (d) melting the metal powder to form the brazing bond.

According to the present invention, in the brazing bond type diamondtool, the tip portion of the shank is thinner than the shank body. As aresult, when a brazing bond layer includes diamond particles, theoverall thickness of the cutting section becomes similar to thethickness of the shank body. Accordingly, the brazing bond type diamondtool may have improved cuttability through a thin cutting section.

In addition, in the brazing bond type diamond tool according to thepresent invention, the shank body has a thickness of at least 1.0 mm,thereby preventing the diamond tool from trembling during rotation athigh speed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will become apparent from the detailed description of thefollowing embodiments in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a perspective view of a brazing bond type flat blade-shapeddiamond tool in accordance with one embodiment of the present invention;

FIG. 2 is a sectional view of one example of a brazing bond layer formedon a shank in which a shank body has the same thickness as that of a tipportion of the shank;

FIG. 3 is a sectional view of one example of a brazing bond layer formedon a shank in which a tip portion of the shank has a smaller thicknessthan a shank body;

FIG. 4 is a flowchart of a method of manufacturing a brazing bond typediamond tool in accordance with one embodiment of the present invention;and

FIG. 5 is a graph depicting a relationship between cutting time andparticle size of diamond particles.

DETAILED DESCRIPTION

Embodiments of the present invention will now be described in detailwith reference to the accompanying drawings. It should be understoodthat the present invention is not limited to the following embodimentsand may be embodied in different ways, and that the embodiments aregiven to provide complete disclosure of the present invention and toprovide thorough understanding of the invention to those skilled in theart. The scope of the invention is limited only by the accompanyingclaims and equivalents thereof. Like components will be denoted by likereference numerals throughout the specification.

FIG. 1 is a perspective view of a brazing bond type flat blade-shapeddiamond tool in accordance with one embodiment of the present invention.

Referring to FIG. 1, a brazing bond type diamond tool includes a shank110 and a brazing bond layer 120.

The shank 110 is made of steel such as carbon tool steel, alloy toolsteel, and the like, and corresponds to a main body of the diamond tool.

The shank 110 may be divided into a body formed at a central region ofthe shank and a tip portion formed along an edge of the body. Althoughthe body is not distinguished from the tip portion via a clear border,an edge of the shank having a brazing bond layer formed thereon may beregarded as the tip portion.

According to the present invention, the tip portion of the shank 110 hasa lower thickness than the body thereof. This structure will bedescribed in more detail below with reference to FIG. 2 and FIG. 3.

The brazing bond layer 120 is formed on the tip portion of the shank andhas diamond particles 121 secured by a brazing bond 122. The brazingbond 122 may be formed by brazing a metal powder.

FIG. 5 is a graph depicting a relationship between cutting time andparticle size of diamond particles.

Referring to FIG. 5, as the average particle size of the diamondparticles decreases in terms of mesh value, that is, as the size of thediamond particles increases, cutting time is decreased, therebyproviding good cuttability. Here, if the size of the diamond particlesis excessively large, the diamond particles cannot be stably secured bythe brazing bond.

Thus, the diamond particles 121 secured by the brazing bond layer 120may have an average particle diameter ranging from 25 to 50 mesh.

If the average particle diameter of the diamond particles is less than25 mesh, the diamond tool has good cuttability. However, in this case,the diamond particles have an excessively large particle size, and thusthe brazing bond does not stably secure the diamond particles, so thatthe diamond particles can be easily separated from the shank, therebyreducing the lifespan of the diamond tool.

On the contrary, if the diamond particles have an average particlediameter exceeding 50 mesh, the diamond particles have an excessivelysmall particle size, and thus an exposed height of the diamond particlesfrom the brazing bond layer is low, thereby causing deterioration incuttability of the diamond tool.

The brazing bond may be formed by brazing a Ni-based metal powder, whichcomprises 1˜10 wt % of silicon (Si), 5˜15 wt % of chromium (Cr), 5˜15 wt% of cobalt (Co), and the balance of nickel. The brazing bond composedof the metal powder having this composition advantageously exhibitsexcellent coupling force with respect to steel, which is used as amaterial for the shank.

In the nickel-based metal powder, cobalt and chromium assist in chemicalcoupling between the brazing bond, the diamond particles and the shank.

Each of chromium and the cobalt may be present in an amount of 5˜15 wt %based on the total weight of the brazing bond. If the amount of chromiumor cobalt is less than 5 wt %, the coupling force between the brazingbond and the diamond particles or the shank is low, causingdeterioration in lifespan of the diamond tool. On the contrary, if theamount of chromium or cobalt exceeds 15 wt %, the diamond particlesundergo excessive chemical coupling, which causes deterioration instrength of the diamond particles.

Further, in the nickel-based metal powder, silicon serves to improveflowability of the brazing bond formed by brazing the metal powder.

Silicon may be present in an amount of 1˜10 wt % based on the totalamount of the brazing bond. An amount of silicon less than 1 wt %results in insufficient effect obtained by the use of silicon, and anamount of silicon exceeding 10 wt % provides excessively highflowability to the brazing bond, causing the brazing bond to flowinstead of holding the diamond particles.

Further, the nickel-based metal powder may further contain metals suchas boron, phosphorous, tin, and the like in order to enhance theflowability of the brazing bond. In this case, the amount of nickel isreduced corresponding to the amounts of the additional metal components.These additional metal components may be present in an amount of 10 wt %or less based on the total amount of the brazing bond. The amount of theadditional metal components exceeding 10 wt % provides excessively highflowability to the brazing bond, causing the brazing bond to flowinstead of holding the diamond particles.

FIG. 2 is a sectional view of one example of a brazing bond layer formedon a shank in which a shank body has the same thickness as that of a tipportion of the shank, and FIG. 3 is a sectional view of one example of abrazing bond layer formed on a shank in which a tip portion of the shankhas a smaller thickness than a shank body.

A section of the diamond tool participating in cutting (hereinafter,“cutting section”) may be composed of the tip portion and the brazingbond layer 120 of the shank 110. As described above, as the cuttingsection becomes thinner, the cutting plane becomes sharper, therebyproviding better cuttability.

Reduction in thickness of the cutting section may be achieved byreducing the thickness of the shank or the size of the diamondparticles. However, when the shank has a small thickness, the diamondtool is likely to tremble during rotation at high speed, and when thediamond particles have a small size, the diamond tool can bedeteriorated in cuttability. Accordingly, a conventional brazing bondtype diamond tool has a limit in improvement of cuttability.

On the other hand, the present invention provides a brazing type diamondtool which has a unique shank structure so as not to suffer fromtrembling during rotation at high speed while ensuring good cuttability.In a conventional brazing bond type diamond tool as shown in FIG. 2, theshank body has the same thickness as that of the tip portion. Thus, thecutting section of the diamond tool including the tip portion and thebrazing bond layer of the shank has a thickness represented by T1+2×T2.On the other hand, for the brazing bond type diamond tool according tothe present invention as shown in FIG. 3, the cutting section of thediamond tool including the tip portion and the brazing bond layer of theshank has a thickness represented by T3+2×T2.

Here, in the brazing bond type diamond tool shown in FIG. 3, thethickness (T3) of the tip portion is less than the thickness (T1) of thebody (T3<T1). Thus, it is possible to achieve the effect of reducing thethickness of the cutting section. Accordingly, the brazing bond typediamond tool may have improved cuttability.

On the other hand, in the brazing bond type diamond tool shown in FIG.1, the body of the shank 110 has a thickness T1 greater than thethickness T3 of the tip portion (T1>T3). This structure is conceived toprevent the diamond tool from trembling during rotation at high speed bysecuring a desired thickness of the shank.

If the shank 110 has too low a thickness, the diamond tool suffers fromtrembling during rotation at high speed. Such trembling causesdeterioration in cuttability and lifespan of the diamond tool and doesnot guarantee operator safety. However, according to the presentinvention, only the tip portion of the shank 110 is reduced in thicknessand the body is increased in thickness, thereby preventing the diamondtool from trembling during rotation at high speed.

In some embodiments, the body of the shank 110 may have a thicknessranging from 1.0 mm to 3.0 mm. If the body of the shank 110 has athickness of less than 1.0 mm, the diamond tool can suffer fromtrembling during rotation at high speed and does not guarantee linearcutting due to bending of the shank during cutting. If the body of theshank 110 has a thickness exceeding 3.0 mm, the diamond tool undergoescuttability deterioration due to thickness increase of the cuttingsection, which includes the tip portion and the brazing bond layer 120.

Although the flat blade-shaped diamond tools are illustrated as theexamples of the brazing bond type diamond tool in FIGS. 1 and 3, thepresent invention is not limited thereto. The present invention may beapplied to brazing bond type diamond tools of different shapes, such asa cup shape, a core drill shape, and the like.

FIG. 4 is a flowchart of a method of manufacturing a brazing bond typediamond tool in accordance with one embodiment of the present invention.

Referring to FIG. 4, the method of manufacturing a brazing bond typediamond tool according to this embodiment includes preparing a shank(S410), depositing a metal powder (S420), setting diamond particles(S430), and forming a brazing bond (S440).

In operation of preparing a shank (S410), a shank including a body and atip portion formed along an edge of the body is prepared. Here, the tipportion of the shank has a lower thickness than the body.

As described above, the shank including the tip portion thinner than thebody is used. The body of the shank preferably has a thickness of 1.0 mmor more, more preferably in the range from 1.0 mm to 3.0 mm.

Next, in operation of depositing a metal powder (S420), a metal powderfor a brazing bond is deposited on the tip portion of the shank.

The shank may be subjected to cleaning to remove foreign matter from thesurface of the shank before deposition of the metal powder. Cleaning maybe carried out in various ways such as plasma cleaning, alcohol or watercleaning, and the like.

It is advantageous that the prepared metal powder exhibits good couplingforce with respect to the shank and diamond particles. In someembodiments, the metal powder may be a Ni-based metal powder, whichcomprises 1˜10 wt % of silicon (Si), 5˜15 wt % of chromium (Cr), 5˜15 wt% of cobalt (Co), and the balance of nickel.

The metal powder may be deposited on one or both sides of the tipportion of the shank 110. Alternatively, as shown in FIG. 3, the metalpowder may be deposited to surround the tip portion of the shank 110.

Next, in operation of setting diamond particles (S430), diamondparticles are set on the tip portion of the shank having the metalpowder deposited thereon.

In consideration of cuttability, the diamond particles may have anaverage particle size ranging from 25 to 50 mesh.

Diamond particle setting may be carried out using a jig, by dropping thediamond particles, or the like.

A mixture of diamond particles and metal powder can be deposited on theshank. However, in this case, there can be difficulty in achievinguniform dispersion of the diamond particles due to a large difference inspecific gravity between the metal powder and the diamond particles.Thus, uniform dispersion of the diamond particles is advantageouslyobtained by depositing the metal powder on the tip portion of the shank,followed by setting the diamond particles on the metal powder.

Then, in operation of forming a brazing bond (S440), the metal powder ismelted to form a brazing bond. More specifically, the metal powder isheated above a melting point of the metal powder to melt the metalpowder, followed by cooling to form the brazing bond, which secures thediamond particles.

In this operation, the metal powder is heated to a temperature higherthan or equal to the melting point of the metal powder and less than amelting point of the shank. More specifically, the melting temperatureof the metal powder may be determined according to the composition ofthe metal powder deposited on the tip portion of the shank.

For example, when a metal powder comprising 1˜10 wt % of silicon (Si),5˜15 wt % of chromium (Cr), 5˜15 wt % of cobalt (Co), and the balance ofnickel is deposited on the tip portion of the shank, the meltingtemperature of the metal powder may be set in the range from 980˜1200°C. in the operation of forming a brazing bond (S440).

If the melting temperature is less than 980° C., there can be difficultyin melting the metal powder. If the melting temperature exceeds 1200°C., there can be problems of diamond carburization and increase inmanufacturing cost due to heating to high temperature.

Meanwhile, cooling of the metal powder melt may be performed in variousways including forcible cooling, natural cooling, and the like. Here,cooling may be performed within a furnace used for forming the brazingbond.

As described above, in the brazing bond type diamond tool according tothe present invention, the tip portion of the shank is thinner than theshank body. As a result, the overall thickness of the cutting section isreduced, thereby improving cuttability. In addition, the thickness ofthe shank body is maintained at a certain level, thereby preventing thediamond tool from trembling during rotation at high speed.

Although some exemplary embodiments have been described herein, itshould be understood by those skilled in the art that these embodimentsare given by way of illustration only, and that various modifications,variations, and alterations can be made without departing from thespirit and scope of the present invention. Therefore, the scope of thepresent invention should be interpreted according to the followingappended claims as covering all modifications or variations induced fromthe appended claims and equivalents thereof.

1. A diamond tool comprising: a shank having a body and a tip portionformed along an edge of the body, the tip portion being thinner than thebody and integrally formed with the body; and a brazing bond layerformed on the tip portion of the shank to secure diamond particles witha brazing bond.
 2. The diamond tool according to claim 1, wherein thebody has a thickness ranging from 1.0 mm to 3.0 mm.
 3. The diamond toolaccording to claim 1, wherein the diamond particles have an averageparticle diameter ranging from 25 to 50 mesh.
 4. The diamond toolaccording to claim 1, wherein the brazing bond comprises 1˜10 wt % ofsilicon (Si), 5˜15 wt % of chromium (Cr), 5˜15 wt % of cobalt (Co), andthe balance of nickel.
 5. The diamond tool according to claim 1, whereinthe diamond tool is a flat blade type diamond tool.
 6. A method ofmanufacturing a diamond tool comprising: (a) preparing a shank includinga body and a tip portion formed along an edge of the body, the tipportion being thinner than the body and integrally formed with the body;(b) depositing a metal powder for forming a brazing bond on the tipportion of the shank; (c) setting diamond particles on the tip portionhaving the metal powder deposited thereon; and (d) melting the metalpowder to form a brazing bond.
 7. The method according to claim 6,wherein the body of the shank has a thickness ranging from 1.0 mm to 3.0mm.
 8. The method according to claim 6, wherein the metal powdercomprises 1˜10 wt % of silicon (Si), 5˜15 wt % of chromium (Cr), 5˜15 wt% of cobalt (Co) and the balance of nickel, and the melting the metalpowder comprises melting the metal powder at 980-1200° C. to form thebrazing bond.
 9. The method according to claim 6, wherein the diamondparticles have an average particle size ranging from 25 to 50 mesh.